War, and the social changes and upheaval it brings, often creates trends that reach well outside the battlefield as people adjust to the conflict and soldiers bring new culture home. One curious example of changes brought about as a result of war is the rise in popularity of the two piece pajama set among women.

During World War I, the advent of German Zeppelin (and later plane) driven bombing raids against the British shifted the cultural behaviors around the evening hours and sleep. Women, used to retiring to the privacy of their homes in the evening, now found themselves thrust back into the public sphere as they and their families rushed to hide in community air raid shelters. As a result of this shift, women began adopting pajama-style sleepwear over nightgowns for both practical and social reasons.

First, the practical: it was far easier to race through your town to the air raid shelter if you were wearing pants and a top instead of a billowing night gown. Second, the social: despite the terror of the bombings themselves and the disruption the war injected into the lives of the British people, nobody wanted to look unkempt or disheveled. There was a huge market for women’s pajamas in many different fabrics and patterns, along with head wraps, caps, and head scarves—all items that helped British women, under stress, keep up the pretense of having their lives together and orderly.

After the war ended and the threat of air raids faded, the fashion had permanently shifted and women’s pajamas remain, to this day, a sleepwear staple.